The CKiD Study is a multi-center, cohort study of children aged 1 to 16 years with mild to moderate impaired kidney function. Two clinical coordinating centers (CCCs) (at Children's Hospital of Philadelphia and at Children's Mercy Hospital in Kansas City), a central biochemistry laboratory (at the University of Rochester), and a data coordinating center (at Johns Hopkins School of Public Health) have formed a cooperative agreement to conduct a prospective study of chronic kidney disease in children. Since its inception in 2003, the scientific aims of CKiD have been to determine the risk factors for decline in kidney function and to define how progressive decline in kidney function impacts biomarkers of risk factors for cardiovascular disease; neurocognitive function and behavior; and growth failure and its associated morbidity. The purpose of this application is to request funds to continue the cohort study from August 2013 to July 2018. The substantive scientific aims are described in the application from the collaborating CCCs. This application describes the role that the Kidney Disease in Children Data Management and Analysis Center (KIDMAC) will perform as the Data Coordinating Center of the study. We will continue to provide leadership in study design, coordination and conduct, data management and analytical methodology and thereby enhance the scientific scope of CKiD. The specific aims of KIDMAC are: 1) to continue providing biostatistical and epidemiological study design expertise including methods to appropriately nest case-cohort sub- studies; 2) to continue providing the Steering Committee, the two clinical coordinating centers, the central biochemistry laboratory and the scientific subcommittees with an infrastructure to coordinate and conduct CKiD research activities, data acquisition and protocol and form development and revisions; 3) to continue maintaining and enhancing the KIDMAC-developed web-based system to manage the data of CKiD; 4) to continue providing biostatistical and epidemiological leadership in the analysis, interpretation and presentation of study-wide initiatives including the development of methods for the appropriate analyses of the CKiD data (e.g., usage of time since CKD diagnosis as time scale for analysis, non-linear trajectories, joint survival and longitudinal data analysis, and methods fr causal inferences); and 5) to continue implementing a quality assurance program that integrates expertise in data management, study coordination, statistical methodology and scientific disciplines. KIDMAC investigators have expertise in research design, coordination, data management, quality assurance and epidemiological and biostatistical methods for complex longitudinal and survival data.